Otto lujtdell



0. LUNDELL May 10, 1932.

BROACH Original Filed Nov. 29, 1926 I INVENTOR Otto lam/655. BY J g ATT RNEY6.

Reissued May 10, 1932 UNITED STATES PATENT OFFICE OTTO LUNDELL, OF DETROIT, MICHIGAN, ASSIGNOR TO COLONIAL TOOL COMPANY, O

DETROIT. MICHIGAN, A CORPORATION OF MICHIGAN BROACH Original No. 1,708,478, dated April 9, 1929, Serial No. 151,338, filed November 29, 1928. Application for reissue filed December 26,

It is the primary object of my invention to provide means for'lessening the amount of efi'ort necessary to be exert-ed'in pulling a broach, having cutting teeth thereon,through the work being operated-upon. It is quite customary in the conventional'building of broaches to provide the sides of the cutting teeth with straight faces. faces bear against thesides of the splines or the like which are being cutby the teeth and add greatly to the amountv of effort necessary to pull the broach through the work. This is'particularly true when the broach has become heated so as to expand to a greater than normal width. I

It is therefore an object of my invention to relieve the sides of the teeth, longitudinally of the broach, in proportion to the height of the cutting teeth so. as to provide a nearl constant side bearing portion for the teet and a non-bearing portion on the sides of the teeth which increases as the height of the teeth increases.

With the above and other objects in view, my invention consists in the arrangement, combination and construction of the various parts of my improved device,-as described in the specification, claimed in my claims, and

shown in the accompanying drawings, in

which .Fig. 1 is an elevation of a breach embodying my invention.

Fig. 2 is a sectional view taken on line 2-2. of Fig. 1.

Fig. 3 is a sectional view taken on line 3 3 of Fig. 1 and Fig. 4 is a broken plan view of a finished work piece illustrating the cutting operation performed by my'broach.

I have shown a broach provided with a conventional central portion 5, chip receiving channels 6 and teeth 7. Theteeth 7 may be provided with central reliefs or cut away por-' tions 8, but it is to be understood that the teeth may be flat or of arcuate shape as conventionally-employed in the-art. As is usual the teeth 7 increase in height or depth from the front to the rearof the broach. This increase in height or depth is clearly illustrated by the two cross sectional These straight 1930. Serial no. 504,963.

of the broach during the splining operation.

The material machined from the base of the spline falls within the chip receiving channels 6 which carry it outside of the confines of the hub.

As the depth of the teeth 7 increases toward the finishing end of the broach, a considerable depth is attained and if the sides of the teeth are straight so as to bear in the sides ofthe splineswhich are being cut, a consider able friction is set up with a consequent increase in the amount of effort required to pull the broach through the work. As is clearly shown, however, in Fig. 2 the teeth are provided with relatively short straight portions and relatively long relieved or inwardly tapered portions 10 which relieved or inward 1y tapered portions do not bear against the splines being cut. It is tobe understood that therelieved or tapered portion may be of any form to efi'ect a recess below the short.

shown by the longitudinal lines in Fig. 1, the 4 depth of the relieved or inwardly tapered portions onthe various teeth decreases from the final to the initial cutting end of the broach. The straighter unrelieved portion remains substantially constant until teeth are of such shallowness as to bring the side portions thereof substantially to a point, as is clearly shown in Fig. 3.

The hub 12 of the gear 13 is illustrated as having four equally spaced slots or splines 14:- out in its inner periphery by my broach in a single operation. By'having the teeth of the broach recessed, the four splines may be out at the same time with comparative ease since allot the applied force is equally distributed along the top and side cutting edges of the four rows of teeth and is entirely utilized for the cutting operation.

relieved sides to a teeth at ,a height from the base within which preceding teeth are provided with side cutting edges.

This theory of relieving the teeth against frictional contact with the major portion of the side walls ofthe groove cut by the precedingteeth may, of course, be applied to breaches having teeth of an entirely different "*shape from that illustrated, and likewise the inventionimay be applied to breaches of differentstyle and construction from that shown and irrespective ofrthe number efrows-of ,cuttingteeth on the breach. I

It will be obvious that variouschanges may ber made in the arrangement, combina tion and constructionof the various parts of my improved device without departing from thefspirit of my invention and it is my in-- 'tentionto cover by my claims suchchanges as may be reasonably included scope thereof.

What I claim is:

i A breach or the like havinga plurality within the d'f teeth provided with cutting end portions,

:1 portion of the sides lof said teeth being straight and a portion thereof tapering in wardly. the straight portions being adiacent the cutting ends of the teeth, and the taper,-

ing portions being of increasing depth to+ ward the finishing end. of the breach. 7

2. A breach-or the like having a plurality of'teeth provided with cutting end-portions, a portion of thesides of said teeth being straight-and. a portion thereof tapering inwardly.; the straight portions being adiaccnt theycutting ends of. the teeth and being-of substantially the same depth on substantially allof'the teeth and. the tapering'portions being of increasing depth toward the finishing end of the breach.

A breaching tool. for cuttinga groove in a member, said toolhaving a body portion upon which a plurality of cutting teeth-are provided in a row, cutting edges on'theltop upon which a plurality of cutting teethfare of, said teeth which extend a slight distance on thesides thereof. the sides of the teeth below the top side cutting edges and out- 4 wardly of said bodv portion being of 6 width" than the width of the side cutting a s v. in a member ising 'a body portion on edges of preceding teeth;

a me mb'er, said tool including a body portion A breaching tool for cutting a groovelilr provided in a row, cutting edges on the top and the two sides of each tooth provided in such manner that substantially all of the side edges of the teeth inwardly of the cutting edges and outwardly of said body portion are-cut away to relieve the said cut away sides from contact with a plane tangent to the side cutting edges of the preceding teeth.

5. A breaching tool for cutting a groove in a member including a body portion on which a row of teeth is provided of gradually increasing height from one end of the tool to theother, cutting edges on the top of said teeth which extend a short distance on each side thereof in such manner as to have the side cutting edges of adjacent teeth provide a continuous contour and have the portion of the teeth below the side cutting edges of less width than the side cutting edges of precedin g teeth.

6. A breaching tool provided with a row of teeth for cutting a groove in a member, cutting edges on the top of the teeth in progressive offset relation to each other relative to the axis of the tool, the sides of the teeth below the top cutting edges and outwardly of the body of the tool being of less width than the width of the cutting edges of preceding teeth.

7. A breaching tool provided with a row of teeth for cutting a groove in a member, cutting edges on the top of the teeth in progressive offset relation to each other relative to the axis of the tool, the sides of the teeth below the top cutting edges and outwardly of the body of the tool being relieved inwardly from the portions of the groove cut by preceding teeth.

8. A breaching tool for cutting a plurality ofgroovcs in a member, said tool having a body portion upon which a plurality of cut- .ting teeth are provided in rows, cutting edges on the top of said teeth which extend a slight distance on the sides thereof, the side cutting edges of one tooth being a continuation of v the side cutting edges of an adjacent tooth :and the sides of the teeth below the side cutting edges being of less width than the width of the side cutting edges of preceding teeth;

9'. A breaching tool having a rowef teeth of increasing height thereon which conforms to the shape of the groove to be cut. a" cutting edge on the top portion of each teeth which extends downwardly on each of its sides afldistance short of the length of the tooth, the portion of the sides of the teeth below their cutting edges and outwardly of the bodwof. the tool being of less width than the width got the groove 'cutby the side cut ting edges of preceding'teeth.

10. A breaching tool for cuttinga groove tool tothe other, the sides of said teeth located outwardly of the body of the tool being relieved from contact with the major portion of the side walls of said groove as cut by the preceding of said teeth.

5 11. A broaching tool for cutting a plurality of grooves in a member comprising a body portion on which a plurality of rows of teeth are provided which gradually increase in height from one end of the tool to the other, the sides of said teeth located outwardly of the body of the tool being relieved y from contact with the major portion of the side walls of said grooves as cut by preceding teeth of each row.

- In testimony whereof I have hereunto subscribed my name this 24th day of December, 1930.

OTTO LUNDELL. 

